7. A train overtakes 2 persons walking \( 2 \mathrm{~km} / \mathrm{hr} \) and \( 4 \mathrm{~km} / \mathrm{hr} \) respectively in the same direction and completely passes them in 9 seconds and 10 seconds. What is the speed of the trains in \( \mathrm{km} / \mathrm{hr} \) ? \( \begin{array}{llll}\text { 1) } 13.2 & \text { 2) } 17.6 & \text { 3) } 22 & \text { 4) } 26.4\end{array} \)

Example 10 Three coplanar forces of magnitudes \( F, 5,3 \) Newton act on a particle and the measure of the angle between the second the third force is \( 60^{\circ} \). Find the value of \( F \) if the forces are in equilibrium.

Describe the law of conservation of momentum as it pertains to a real-life scenario, and explain how it applies. Begin by identifying the real-life scenario. You may start your response with: - A real-life scenario pertaining to conservation of momentum is ... - In this scenario, the law of conservation of energy applies because . . .

27. Two trains, 1 and 2 , have an equal mass of \( m=5,000 \mathrm{~kg} \) each. Train 1 is traveling with a speed \( n=15 \mathrm{~m} / \mathrm{s} \) before striking train 2 , which was at rest. If the two trains lock together as the result of the collision. What is their common speed immediately after collision?

Train moving with speed of \( (40 \mathrm{~m} / \mathrm{s}) \) the driver have resorted to the use of brakes to reduce the speed of the train movement by rate \( \left(-2 \mathrm{~m} / \mathrm{s}^{2}\right) \) Calculate: a) The amount of time it takes for the train even stops completely. b) The amount of distance traveled since the train began braking until it stops

3.33 • Uma canoa tem velocidade de \( 0,40 \mathrm{~m} / \mathrm{s} \) a sudeste em relação à Terra. A canoa se desloca em um rio que escoa a \( 0,50 \mathrm{~m} / \mathrm{s} \) para leste em relação à Terra. Determine o módulo, a direção e o sentido da velocidade da canoa em relação ao rio.